Young thief “The Bat” to distract an old bookseller, while his partner, “The Fly,” robs the till, purchases a book at random. Later, after a chase and escape to the Devil's Roost, Old Meg's refuge for thieves, he takes the book from his pocket and is about to throw it aside when the title attracts him, "Electricity Made Simple." Intrigued, the volume opens a new life to him and in time enables him to rescue the bookseller’s daughter Bess when she falls into trouble.